No Hot Water? Troubleshooting for Gas & Electric Systems

Updated July 2026 · 8 min read · Geelong Emergency Plumbing

There are two kinds of mornings: normal ones, and the ones that begin with a shower doing its best impression of Bass Strait in July. Before you book anyone, work through this checklist — a decent share of "no hot water" call-outs turn out to be something the householder could have fixed in five minutes, and the rest of the time you'll at least know exactly what to tell the plumber, which shortens the visit you're paying for.

First: The 30-Second Triage

Answer two questions before touching anything. Is it no hot water, or not enough? Completely cold points to a failed component or energy supply; lukewarm or running-out-fast points to thermostats, sediment or an undersized system (different problem, different fixes). Is cold water pressure normal? If both hot and cold are misbehaving, your problem is the water supply, not the hot water system — check whether the mains or a meter valve has been disturbed.

Gas Hot Water: The Checklist

1. Is the pilot light out?

The most common culprit on storage systems. Look through the sight glass at the bottom of the unit — no small blue flame means no ignition. Relighting instructions are printed on every unit (usually behind the access panel): typically turn the gas control to PILOT, hold it down, click the igniter, keep holding 30–60 seconds, then turn to ON. If it lights and stays lit, you've just saved a call-out fee. If it lights and dies the moment you release the button, the thermocouple — the safety sensor that confirms the flame exists — has likely failed. That's a cheap part but a licensed-gasfitter job.

2. Do you actually have gas?

Check another gas appliance like the cooktop. Nothing anywhere? Check the meter valve hasn't been turned off (lever across the pipe = off), whether LPG bottles are empty, and whether your retailer has any supply interruption notices. It happens more than anyone admits.

3. Windy night?

Exposed units can have pilots blown out by weather — one relight and you're done. If it happens repeatedly, the unit's draught protection needs attention, because relighting the pilot shouldn't become a hobby.

4. Continuous-flow unit showing an error code?

Instantaneous systems display fault codes on the controller — note the code before resetting (power off 60 seconds, on again). A code that returns after reset is diagnostic gold for the technician; tell them on the phone and they arrive with the right parts.

Electric Hot Water: The Checklist

1. Check the switchboard

Find the breaker labelled "hot water" or "HWS." Tripped? Reset it once. If it holds, you were the victim of a random trip and hot water returns in an hour or two (storage systems reheat slowly — patience, not panic). If it trips again immediately, stop. A repeatedly tripping hot water circuit usually means a failed element or wiring fault — leave it off and call. Resetting it a fifth time is not a repair strategy.

2. Remember off-peak

Many electric systems run on off-peak tariffs that only heat overnight. A house full of teenagers can drain the tank by 8am, after which no reheating happens until tonight — the system isn't broken, it's rationing. If this is a weekly event, the tank is undersized for the household.

3. The element and thermostat

Heating elements and thermostats are the wear items of electric storage — they fail with age, and sediment build-up accelerates it. Replacement is a routine repair, but it involves mains voltage and stored water: licensed territory, not a YouTube afternoon.

Faults Common to Both

• Leaking tank: water pooling under the unit from the tank body (not the relief valve) means the cylinder has corroded through. That's not repairable — it's a replacement conversation, and our cost guide covers what comes next.
• Pressure relief valve running constantly: occasional dripping during heating is normal; a steady stream is a failed valve — a small, common repair worth doing promptly.
• Tempering valve failure: if hot water is suddenly lukewarm everywhere but the system seems fine, the tempering valve (which blends hot down to a safe 50°C at bathroom taps) may have failed cold. Very common, very fixable.
• Age: if your system is past 8–12 years, any significant fault triggers the repair-vs-replace question — see how long systems last for the honest maths.

When It's Definitely Time to Call

Pilot won't stay lit, breaker won't hold, error codes that return, any tank-body leak, no gas anywhere, or you've simply reached the limit of what's safely DIY — gas and mains-voltage work are licensed for good reasons. A same-day repair beats a week of kettle showers, and if the diagnosis is terminal, most standard replacements happen the same day too. Cold showers build character; you likely have enough already.

FAQs

Related guides: Hot water system cost guide · How long do hot water systems last · Hot water repairs Geelong